hive-forge: add markdown-docs generator and CI freshness check

docs/tools/forge.md

@@ -4,6 +4,14 @@
 container (installed via `nix/agent-modules/forge.nix`, on `PATH` as a
 proper Rust binary). Use it instead of ad-hoc curl pipelines.
 
+This page is the curated guide. For the exhaustive flag-by-flag reference
+auto-generated from the binary's own command tree, see
+[`forge-cli.md`](forge-cli.md) — emitted by the hidden `hive-forge
+markdown-docs` subcommand and kept in lockstep with the code by the
+`hive-forge-docs` flake check (CI fails if the committed copy drifts).
+Regenerate with `nix build .#hive-forge && ./result/bin/hive-forge
+markdown-docs > docs/tools/forge-cli.md`.
+
 ## Credentials and repo defaults
 
 - Credentials: `$HYPERHIVE_STATE_DIR/forge-token`